Composite Alginate–Quince–Flaxseed Microcapsules for Enhanced Gastrointestinal Survival of Lacticaseibacillus rhamnosus GG

Abstract

Low gastrointestinal survival of probiotic microorganisms is still a significant hurdle for the use of probiotics in functional foods. The aim of the present study was to develop composite alginate-based microcapsules of Lacticaseibacillus rhamnosus GG using the combination of Quince seed mucilage (QSM) with flaxseed mucilage (FSM) to enhance the stability and targeted intestinal delivery of L. rhamnosus GG. The four formulation types were sodium alginate (SA), alginate–quince mucilage (SA-QM), alginate–flaxseed mucilage (SA-FM), and alginate–quince–flaxseed mucilage (SA-QFM), and were subjected to various physicochemical evaluations, gastrointestinal protection, storage stability, and in vitro release studies. Among the formulations, SA-QFM exhibited the highest encapsulation efficiency (96.18%), followed by SA-FM (93.84%), SA-QM (86.37%), and SA (81.42%). SA-QFM also generated the largest and most compact microcapsules (982.7μm) with excellent mechanical properties and minimum swelling index. After sequential simulated gastrointestinal exposure, the probiotic viability was maintained at 88.55% (SA-QFM) and 43.04% (free cells), with retention of 8.12 log CFU/g and 3.96 log CFU/g, respectively. Likewise, SA-QFM exhibited the maximum bile salt tolerance (8.58 log CFU/g), with the highest bile salt tolerance survival (93.57 log CFU/g, 0.42%). The maximum viability after refrigerated storage at 4 °C (8.84 log CFU/g) and the maximum cumulative release in SIF (98.4%) were observed for SA-QFM. In conclusion, the synergistic effect of the quince seed and flaxseed mucilage enabled the alginate matrix to become highly protective and efficiently release the probiotics in the gastrointestinal tract. The developed SA-QFM microcapsules could be a promising natural delivery system for incorporating viable probiotics into functional foods and nutraceutical products.